The "Wave Eight" survey, conducted by market research firm Advertiser Perceptions, asked marketers representing consumer package goods, automotives, retail and other sectors to weigh in on the current type of mobile ads they used and their planned media spending for those ads in the next six months.

Podcast and video
Podcasts and video saw the biggest decline from April and May of 2007 to October and November of 2007, with the percentage of marketers who use podcasts dropping from 33% to 24% and the percentage of marketers who use video dropping from 31% to 29%.

But don't count video mobile ads out just yet. As mobile devices become better equipped with video technology, opportunities for marketers will get better and better, said John Hadl, CEO of Brand in Hand, a mobile adviser to major brand marketers such as Procter & Gamble Co.

"Video is the most promising of all [the types of mobile ads]," he said. Indeed, the percentage of marketers who plan to use video within the next six months has increased from 39% to 42%.

Of all the mobile ads used, text was the most popular, with about 70% of respondents saying they currently use text ads and 69% planning to use them in the next six months.

Scale and reach
Mr. Hadl said marketers are drawn to text over other categories because it has the most scale and reach. Banner ads, another type of mobile ad with reach, were the second most used ads by respondents.

With 36% of respondents saying they currently use it, search was ranked as one of the least used type of mobile ads. However, it also had one of the highest percentages (45%) of respondents saying they plan to use it in the next sixth months. Like video, search has a lot of potential for marketers as technology continues to evolve, Mr. Hadl said.

Where are marketers placing their mobile ads? An increasing number of respondents said they prefer to place their ads on wireless carriers, while a decreasing number said they preferred to place their ads on content providers, such as ESPN and Yahoo. This trend could signal that marketers will start to make more deals with the wireless carriers themselves, said Ken Pearl, the CEO of Advertiser Perceptions.

Split over use
In the big picture for mobile, marketers in the survey were split usage-wise -- 26% said they were currently using mobile, 20% said they planned to use it in the next six months, and 54% said they are not currently using mobile.

The reason for this split, said Steve Lanzano, chief operating officer of Havas media agency MPG, is that that advertisers are still figuring out to how best to take advantage of mobile.

"It will be very interesting to see how people use a mobile phone when they develop more capabilities," he said, noting that he thinks search will emerge as one the top spending categories. "A lot of people are going to look to Asian markets [for guidance]," he said.